1. Field of the Invention
The present invention relates to a method of manufacturing cyclic carbonate and, more particularly, to a method of manufacturing cyclic carbonate by conducting the cyclization of carbon dioxide and epoxide under the performance of an ionic liquid polymer.
2. Description of the Related Art
Generally, cyclic carbonate is obtained via a phosgenation method, by mixing carbon monoxide and chlorine to obtain phosgene (also known as COCl2), and triggering off a reaction of the phosgene and phenol or ethanol. For example, bisphenol and phosgene are prepared and carried out a synthesis reaction of cyclic carbonate under the performance of alkaline solution and dichloromethane, wherein the co-product of the synthesis reaction of cyclic carbonate is hydrochloric acid. However, due to the toxicity of phosgene and dichloromethane, the above synthesis method of cyclic carbonate is highly risky to human and natural environment, and which may imply potential dangers or pollutions.
Currently, carbon dioxide has replaced the phosgene and becomes a main material for synthesis of cyclic carbonate, by cyclizating carbon dioxide and epoxide to produce cyclic carbonate. Generally, the carbon dioxide used in the synthesis of cyclic carbonate is mainly recycled from the co-products of various industries, for example, fermentation industry, petrochemical industry and metalworking industry, and therefore, the synthesis of cyclic carbonate can be achieved in a not only eco-friendly, but economic and convenient pathway.
As disclosed in a journal article reported by Parshall in 1972 and Kim et al. in 2003, a conventional synthesis method of cyclic carbonate is provided by recycling carbon dioxide from various industries, conducting a cyclization of the recycled carbon dioxide and epoxide under the performance of an ionic solution, and finally generating cyclic carbonate. The said conventional synthesis method for cyclic carbonate comprises a step of “catalytic preparation,” by preparing an ionic solution of 1-butyl-3-methylimidazolium bromide [also known as (Bmim)Br], which is in the form of sticky liquid; a step of “cyclization,” by conducting a cyclization of carbon dioxide and propylene oxide in a stainless reactor, under the catalysis of zinc oxide and the (Bmim)Br, to obtain a mixed solution of propylene carbonate; and a step of “isolation,” by isolating liquid propylene carbonate from the mixed solution of propylene carbonate via a distillation method.
Although the said conventional synthesis method of cyclic carbonate improves the disadvantages of the phosgenation method, the catalysis of the ionic solution of the said conventional synthesis still has the following weaknesses. First of all, the said conventional synthesis of cyclic carbonates is a time-consuming and low-efficient process because of the homogeneous catalysis between the ionic solution and the mixed solution of propylene carbonate, and therefore, an additional step of “isolation” is needed after the step of “cyclization” for the sake of isolating liquid propylene carbonate from the mixed solution of propylene carbonate via a distillation method. In this way, the cost and manufacture time of cyclic carbonate will be increased. Second, the distillation method in the step of “isolation” is generally performed by heating the ionic solution and then separating the cyclic carbonate from the ionic solution by their difference of boiling point, so that the quality of the ionic solution may be degraded after heating.
Thus, regarding the disadvantages of the conventional synthesis method of cyclic carbonate, there is a need to provide a new method of manufacturing cyclic carbonate so as to synthesize cyclic carbonate in a more convenient and effective process.